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Today I found Texas Instruments announced a circuit for wireless charging - Ti BQ51013 Qi receiver controller - all the materials emphasis how tiny, lightweight, portable, efficient and otherwise cool it is.

While I of course like the idea I don't get one thing. What's so hard in implementing such circuit in just all cell phones allready? Every other company introduces so-called "charging mats" that also require en extra gadget attached to the wireless device to make it receive power from the "charging mat" and I guess different systems are incompatible with each other, but there're almost no devices with built-in wireless charging (except maybe shavers and toothbrushes).

It's year 2011 and we have microchips with millions of transistors on them - why don't we have such simple thing as wireless charging in every applicable device yet? What's the technical difficulty here?

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    \$\begingroup\$ Because people are willing to buy things without it. :) \$\endgroup\$ – endolith Apr 21 '11 at 14:51
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    \$\begingroup\$ The argument of "It's year wxyz and we have microchips with millions of transistors on them - why don't we have abcd", doesn't usually ever work well. I could use the same argument for so much. Example, with obesity being such a large issue, why not have a sensor built into your phone that tells you your BMI by just holding on to two contacts, one for each hand. It's so simple that even many cheap scales have that technology. Might be simple, and a good idea, but phone companies really don't get much benefit from adding something like this. \$\endgroup\$ – Kellenjb Apr 21 '11 at 15:51
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    \$\begingroup\$ Or, it is the year 2011 and we have all of this great technology, why don't all of our cars have the technology to drive themselves? The technology exists to do this now, but you just need to give it time for cultural and business aspects to change. \$\endgroup\$ – Kellenjb Apr 21 '11 at 15:53
  • \$\begingroup\$ Interestingly, now its 2018 and it hasn't changed. \$\endgroup\$ – Pere Sep 30 '18 at 20:38
  • \$\begingroup\$ @Pere Well, it was very, very overestimated. The whole wireless charging thing is actually not very practical. Your smartphone nearly discharges, you put it onto the charging pad and an IM or an incoming call comes - what do you do? Your shaver unexpectedly discharges and you need to shave urgently - what do you do? It's all much simpler with charging by wire. \$\endgroup\$ – sharptooth Oct 2 '18 at 10:52
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It is still fairly expensive to add to devices.

You have development time and cost since cell phone companies have never added this feature before. I would have to imagine the cost to do this is fairly significant. Cell phone companies will have to do a fair amount of testing to insure that the charging doesn't have any adverse effects on the phone. You can argue that there are already people using these types of chargers on phones, but you have to keep in mind that these systems are still outside of the phone for the most part. When you bring it in to the phone itself there are potentially areas of issue, like inductively coupling to data lines that are already pushing the limits of speed, any extra unwanted noise can be very bad.

You have the cost of the IC and board space. The IC is about $3.50 each. And even though the ICs biggest claim is how small it is, you seem to be forgetting that this IC is new so no one has had a chance to use it yet. But even with how small it is, board space is limited. Figuring out how to fit it all in is extra engineering time and the extra component is slightly additional fabrication cost, maybe only less then a cent more, but these companies are already counting every penny. As @stevenvh mentioned, if you have wireless charging you can remove the external power connector which will save lots of space. However, people still want a USB port. It will be a little while before people are "ok" with the idea of just using bluetooth to transfer data between the phone and computer. In fact there are still phones out there now that have their bluetooth so locked down that you just have to use a USB cable in some situations.

Public view still is not great. There is a large amount of people who are very much against the idea of wireless power. Reasons behind it range from it being less efficient to it causing cancer. You can try to debate these points all you want, but it isn't going to change the minds of people in the general population.

So overall, extra cost that just results in not much gain (at least as of now).

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Give it some time. There are surely advantages to it (space saving: not needing an external power connector, with all the protection that comes with it), so I expect we'll see this in mobile phones in the near future. An attention point may be the size of the antenna.

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There's also the issue of electromagnetic pollution. If you want to charge your device in a reasonable time you'll have to generate a rather strong HF EM field.

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  • \$\begingroup\$ What could be a problem with antenna? Shavers have a very narrow base - much smaller than the back of a phone. In fact whole back of the phone can be covered with wires on the inside and be used as an antenna. \$\endgroup\$ – sharptooth Apr 21 '11 at 13:07
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    \$\begingroup\$ So I assume you design cell phones or have extensive experience taking them apart and analyzing the mechanical packaging? So you'd be qualified to say there's plenty of room in there and none of the materials will block the RF energy to the antenna, and there's room for sufficient shielding of sensitive components from charger EMI and that the charger won't interfere with cellular communication? That the antenna won't heat up and damage any components? You know all that for a fact? \$\endgroup\$ – AngryEE Apr 21 '11 at 16:09
  • \$\begingroup\$ @sharptooth - about covering the whole phone with wires: it still should be usable as a phone, so that antenna, which is much more critical, should also keep working! \$\endgroup\$ – stevenvh Jul 4 '11 at 10:13
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Size is an issue - people want phones to be smaller->less antenna area->less coupling->less power transfer->longer charge time. As I said above, heat may be an issue, RF blocking materials could be an issue, EMI as well, charge rate, blah blah blah. Theoretically it works, but practically not yet.

TI's chip may be good, but if only TI is making it it's expensive. We need Fairchild, Linear, National and all the others to roll out their own solutions as well before this party gets started.

Technology tends to take off when there are large amounts of cheap, effective chips available for a purpose. That's why it took a bit for MP3 to take off after it was created - application-specific integrated circuits that could decode it easily had to license the standard, be created, refined, made smaller, integrate more features (ie, on-chip amplifier, mono/stereo output selection, digital communication bus, etc) and become easier to use before you can have a USB pen that plays MP3s.

Wireless charging will come - I've got one of those wireless charging pads for my Wii-motes and it rocks. Of course, the battery and antenna are integrated together, so it acts just as a battery replacement. You may not be able to do such a thing with phones. Just give it some time.

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It's not just a little chip that gets added to the product, there's also a coil of wire that has to go inside. In a very slim and tightly packed device like a smartphone, there may not be room for it without compromising the design slimness.

The cost is nontrivial. The TI chip is $3.50 just for the receiver IC, while the transmitter side will cost money too, as well as the wire, any passives like capacitors, etc. To go from bill of materials cost to retail is usually about 3x, so wireless power could add some $15 to the price of the product. As most U.S. phones are subsidized by the plan, that's a $15 loss for the carrier unless they can charge more for that model, or increase their subscriber base by attracting new customers with a cool phone.

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  • \$\begingroup\$ $3.50 is for low quantities (1k). Consumer electronics are often produced in quantities of 100k/year, mobile phones even > 1M/year. At those quantities prices will be much lower. You'd be surprised of how cheap things become due to economies of scale. Think of how cheap most consumer products are, and how much it would cost you to build the same. For instance, a PC mother board the size it is, at 6-8 layers will cost you ten times the current price, and it won't be even populated! \$\endgroup\$ – Federico Russo Jul 4 '11 at 10:06
  • \$\begingroup\$ Sure, but since the high volume pricing isn't published, I used what was available as an example. Whether it's $15 or $3, it's still a loss for somebody unless the customer is willing to pay for it. \$\endgroup\$ – Matt B. Jul 5 '11 at 2:34

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